JP3419622B2 - Lithographic printing plate processing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing a lithographic printing plate utilizing a silver complex salt diffusion transfer method, and more particularly to a printing method using an immersion developing method and a coating developing method. The present invention relates to a processing method with improved performance. [0002] A lithographic printing plate utilizing a silver salt diffusion transfer method (DTR method), particularly a lithographic printing plate having a silver halide emulsion layer, is disclosed, for example, in US Patent Nos. 3,728,114 and 4,134,769.
No. 4,160,670, 4,336,321, 4,501,81
No. 1, No. 4,510,228 and No. 4,621,041. [0003] The exposed silver halide crystal undergoes chemical development in the emulsion layer by a development process to become blackened silver, thereby forming a hydrophilic non-image portion. On the other hand, the unexposed silver halide crystals are solubilized by the silver complex salt forming agent in the developer, diffused to the physical development nucleus layer on the surface, and are reduced to ink-acceptable image silver on the physical development nuclei by the reducing action of the developing agent. Precipitates. The DTR method has a mechanism in which chemical development and dissolution physical development proceed simultaneously in a single developer. Therefore, in order to obtain a good printed matter, it is important to balance the speed between the region where the chemical development as the non-image portion occurs and the region where the solution physical development as the image portion occurs. [0005] For example, if the physical solution development is prioritized over the chemical development, it causes the background stain and poor printing durability due to the softening of the image. Conversely, if chemical development takes precedence over solution physical development, poor printing durability will result. [0006] As a plate making processing method that has been put into practical use for a DTR planographic printing plate, an automatic plate making camera having a built-in developing tank is generally used. That is, after exposure with the plate making camera, the printing plate passes through the developer stored in the developing tank,
The developer remaining on the plate after passing is removed by a mechanical method, for example, a method of passing between squeezing rollers having a contact pressure, and then passing through a neutralizing solution tank to adjust the pH of the plate, As in the case of the developer, the neutralizing solution remaining on the plate surface is removed by a mechanical method and dried to form a printing plate. In the plate making method as described above, when the number of sheets to be processed increases due to the running process, there is a gap between the lithographic printing plate processed in the initial stage and the lithographic printing plate after processing a large number of sheets. , There was a difference in the printing performance of the lithographic printing plate.
It is considered that the characteristics of the processing liquid have been changed due to factors such as air oxidation of the processing liquid and contamination by components eluted from the photosensitive material. On the other hand, in recent years, there has been a concern that the effluent of photographic light-sensitive material processing may have an adverse effect on the global environment, and a development system that reduces the amount of photographic processing waste liquid has been demanded. A coating and developing method has been proposed as a processing method. ing. For example, JP-A-48-76603, JP-A-57-115549, JP-A-6-27680, JP-A-6-27682, and Japanese Patent Application No. 5
No. 3,340,028. In the above-mentioned coating and developing method, since processing can be carried out with a small amount of a developing solution as compared with the conventional immersion developing method, development can always be carried out using a new solution, and the problems caused by the running processing as described above hardly occur. . On the other hand, since the amount of the developer used for development is limited, there is a problem that it is difficult to perform sufficient development. In particular, in order to reduce the amount of waste liquid,
When the amount of the developer applied is reduced, the problem becomes conspicuous. That is, in a developing method having a coating mechanism, a new developing solution component is not supplied to the plate surface after coating and supply, and the amount of the developing solution is reduced in order to reduce the waste amount of the developing solution. In addition, the balance between chemical development and physical development is likely to be lost due to slight fluctuation in the properties of the developing solution, which causes a problem that only a printing plate having background smear and poor printing durability can be obtained. Further, in a development processing apparatus having a coating mechanism, when the supplied coating liquid is non-uniform, or when the temperature changes during coating, etc., the area on the processed lithographic printing plate surface is reduced. There was a drawback that a printing plate having different printing characteristics was obtained in some parts. SUMMARY OF THE INVENTION An object of the present invention is to provide a DT
An object of the present invention is to provide a method for stably developing a lithographic printing plate using the R method, and particularly to stabilize a lithographic printing plate during a running process in an immersion developing system and improve printing performance in a coating and developing system. Another object of the present invention is to provide a coating and developing method which can obtain high printing performance even when treated with a small amount of a developing solution in order to reduce the amount of waste liquid. [0013] The above object of the present invention is to provide an undercoat on a support.
Layer, silver halide emulsion layer and physical development nucleus layer in this order.
In the method of processing the provided lithographic printing plate using the silver salt diffusion transfer method , boric acid, silicic acid, ascorbic acid,
Nodiacetate, citric acid, propionic acid and their salts
Comprise at least one weak acid ions are al selected (for
However, at least 0.1 mole per liter of developer
Except when containing ascorbic acid as the main developer
Ku), and pH was achieved by treatment method of a lithographic printing plate, which comprises using a developing solution is 12 or more. The developing device used in the processing method of the present invention is not particularly limited, but is roughly classified into a dip developing device generally used conventionally and a coating mechanism for coating a developing solution on a photosensitive surface. It is a developing device. In the immersion developing device, a photosensitive material is generally conveyed by a pair of conveying rollers to be driven, carried into a processing tank filled with a processing solution, and then carried out of the processing tank after a predetermined time. The capacity of the processing tank depends on the size of the photosensitive material to be processed, but is several liters to several tens of liters. The time during which the photosensitive material is immersed is in the range of 5 seconds to 60 seconds, but is about 3 seconds in a processing method in which a processing tank described below is downsized. Preferably, from 7 seconds to 30
Seconds. In a processing method in which a processing tank is miniaturized as described in Japanese Patent Application Laid-Open No. 4-158360, a photosensitive material carried into a processing liquid tank is carried out in a relatively short time, and a necessary developing time is required. Is such that the development reaction is maintained in the space even after being carried out of the processing liquid tank. In the present invention, a developing method having a coating mechanism is generally a method of applying and supplying a developing solution to a photosensitive surface on which a silver halide emulsion layer is coated.
For example, there are a liquid coating method, a dropping roller coating method, a dropping knife coating method, a spray coating method and a brush coating method described in JP-A-8-76603. A bar coating method using a bar coder (manufactured by ETO CHEMICAL APPARATUS Co.) or the above-mentioned Japanese Patent Application No. Hei 5-33428.
Dip coating method described in JP-A-6-276
No. 80 and No. 6-27682, a method of forming a pool of a developing solution between nips of a pair of non-rotating rod-shaped members, passing a photosensitive material between the nips, and applying the developing solution. is there. The amount of the developing solution applied to the lithographic printing plate is generally in the range of 10 to 80 ml, preferably 20 to 60 ml, per square meter of the printing plate, and the development time (from the application of the developing solution to the (The time until the development effect is stopped) is 3 seconds or more, preferably 3 to 10 seconds. The developer used in the present invention has a pH of 12
That is all. In order to activate a developing agent or a silver halide solvent, a pH of 10 or more is possible, but in a DTR lithographic printing plate in which mechanical strength of printing is required for an image portion,
The pH is 12 or higher, preferably 13 or higher. As described above, hydroxides such as potassium hydroxide and sodium hydroxide have been used as alkaline agents in order to prepare a developer having a high pH. However, when a DTR lithographic printing plate is subjected to multiple plate processing by an immersion method, or in the case of coating and developing, a lithographic printing plate having good printing performance cannot be obtained only with the above alkali agent, and Even if the pH of the developer was further increased, a lithographic printing plate having a high printing durability and sufficient printing performance could not be obtained. In the case of the immersion development system, when a large number of sheets are processed by the running process, the developer becomes contaminated and fatigued, and the printing performance is significantly reduced. On the other hand, in a developing method having a coating mechanism, since the amount of the developing solution is limited, the activity of the developing solution applied on the photosensitive surface is reduced during the developing process, and the printing performance is reduced. As described above, the two developing methods have respective problems, and as a result of various studies, the present inventors have found that a treatment with a developing solution containing a weak acid ion suppresses a decrease in printing characteristics. Was. That is, a weak acid ion expresses a function as a weak alkali only when the existing environment is in a neutral or acidic atmosphere. Therefore, the effect is exhibited only when applied to a high pH developer having a pH of 12 or more, such as a developer for a DTR lithographic printing plate. In particular, when only a small amount of developing solution is supplied onto the photosensitive surface, as in the case of a coating and developing method, the developer penetrates into the emulsion layer of the photosensitive material, and then specifically reduces the developing activity of the film during the developing reaction. It is considered to be suppressed and maintained. By adding a weak acid ion to a developer, a lithographic plate having a high printing durability, which cannot be obtained by simply increasing the pH of the developer or increasing the concentration of potassium hydroxide or sodium hydroxide, etc. I discovered that a printing version could be realized. The sources of the weak acid ions used in the present invention include boric acid and its salts, silicic acid and its salts, and
Scorbic acid and its salts, iminodiacetic acid and its
Salt, citric acid and its salt, propionic acid and its salt
And weak acid and weak acid salt compounds.
Alternatively, two or more kinds can be used in combination. The counterion of the above weak acid salt is not particularly limited, but is preferably lithium, sodium or potassium. The content of weak acid ions in the developer used in the present invention is at least 5 mmol, preferably 20 to 100 mmol per liter. A method of adding a weak acid ion to a developer is to add a weak acid and a weak acid salt compound, which are ion sources, to the developer and then adjust the pH to 12 or more with potassium hydroxide or sodium hydroxide. There is a method in which a weak acid and a weak acid salt compound are added to a developer adjusted to pH 12 or more with sodium hydroxide or potassium hydroxide. In the latter, the pH is readjusted to 12 or higher, if necessary, after the addition of the weak acid and weak acid salt compounds. The developer used in the present invention includes a thickener such as hydroxymethylcellulose, carboxymethylcellulose and polyethylene glycol; an antifoggant such as potassium bromide; compounds described in JP-A-47-262201; A developer such as metol and phenidone can be contained. In carrying out the DTR method, for example, British Patent Nos. 1,000,115, 1,012,476 and 1,017,
As described in the specification of JP-A Nos. 273 and 1,042, 477, it is possible to mix a developer into a silver halide emulsion layer and / or an image receiving layer or another water-permeable hydrophilic colloid layer adjacent thereto. Is being done. Therefore, in such a material, a so-called "alkali activating solution" containing no developer can be used as a processing solution used in the developing step. As the silver halide emulsion of the lithographic printing plate used in the practice of the present invention, silver chloride, silver bromide, silver chlorobromide, silver chloroiodide, silver chlorobromoiodide and the like can be used. Silver is silver halide of 70 mol% or more. These silver halides are spectral sensitizers (spectral sensitizing dyes according to the light source and application, for example, camera type, laser light type, panchromatic type for color separation, etc.), gelatin hardener, coating aid, antifoggant , A plasticizer, a developer, a matting agent, and the like. The binders of the silver halide emulsions include the natural and / or synthetic binders generally used for this purpose,
For example, gelatin, colloidal albumin, cellulose derivatives and the like can be used. Under the silver halide emulsion layer (the surface of the support), a subbing layer for improving adhesion and / or an undercoat layer for the purpose of preventing halation may be included.
Matting agents can also be included. The support on which the silver halide emulsion layer is coated includes
Paper, various films, plastic, paper coated with a substance for resin, metal, and the like can be used. Physical Development The physical development nuclei used for each layer are as follows:
Well-known examples of this type of chemical include metals such as antimony, bismuth, cadmium, cobalt, palladium, nickel, silver, lead, zinc, and sulfides thereof. The physical development nucleus described in JP-A-5-265264 can also be used. Each layer of physical development may contain a developer,
It may contain a water-soluble binder. The lithographic printing plate prepared according to the present invention can be converted or enhanced to ink receptivity by using compounds described in, for example, JP-B-48-29723 and US Pat. No. 3,721,539. The printing method, the desensitizing solution, the humidifying solution, and the like to be used can be a commonly well-known method. EXAMPLES The present invention will be described below with reference to examples, but is of course not limited thereto. Example 1 A lithographic printing plate utilizing the DTR method was coated with an antihalation layer containing silica particles, an ortho-sensitized silver chloride emulsion layer, and a physical development nucleus layer on a subbed-treated polyester film support in this order. Using the width 404mm, length 500mm,
The lithographic printing plate was exposed to a fine line image using a plate making camera having an image reversing mechanism. As the plate making processing solution, the following developer A and neutralizing solution were used. The processing temperatures of the developing solution and the neutralizing solution are 30
And 25 ° C. Developing solution A Potassium hydroxide 15 g Sodium hydroxide 10 g Sodium sulfite 35 g N-aminoethylethanolamine 10 g Weak acid ion 60 mmol Water was added to make 1 liter. The liquid pH is 13.4. Neutralized solution 1 potassium phosphate 36 g sodium sulfite 2 g EDTA-Na 6.25 g Water was added to make 1 liter. As an automatic developing device, a commercially available camera processor CP-414S for DTR planographic printing plates (Mitsubishi Paper Corp.)
/ Dainippon Screen Mfg. Co., Ltd.). The developing solution (7 liters) was filled with the above developer, and the neutralizing solution (6 liters) was filled with the above neutralizing solution, and 100 plates were processed. The lithographic printing plate created by the above operation, 1
The plate and the 100th plate were mounted on a Heidenberg TOK offset printing press, an etching solution was applied all over the plate surface, and printing was performed using a DTR lithographic printing plate humidifying solution. The printing evaluation was performed according to the following criteria. A: A fine line of 100 microns is not lost even when the number is 20,000 or more. B: 100 micron thin line is missing in 15,000 sheets. C: 100 micron fine line is missing in 10,000 sheets. D: 100 micron fine line is missing on 7000 sheets or less. [Table 1] As is apparent from Table 1, by adding a weak acid ion to the developing solution in the immersion developing process, a lithographic printing plate having excellent printing characteristics (printing durability) can be obtained even in the multi-plate process. Was. Example 2 A coating and developing apparatus as described in JP-A-6-27680 was prepared, and the coating amount was adjusted to 40 ml per square meter using the lithographic printing plate and processing solution shown in Example 1. Processed. The printing plate obtained was printed according to Example 1 and evaluated. Table 2 shows the results. [Table 2] From the above results, in the coating and developing system, when a small amount of a developing solution is applied and supplied for development, by adding a weak acid ion to the developing solution, high printing performance which cannot be expected from the conventional developing solution can be obtained. can get. The coating and developing method is different from the immersion method of the first embodiment, and from the standpoint of always processing with a new solution, a stable one can be obtained regardless of the number of processed sheets. According to the present invention, it is possible to obtain a lithographic printing plate utilizing the silver salt diffusion transfer method, which is more stable than before and has good printing characteristics. In particular, stabilization during running processing in the immersion development system and improvement in printing performance in the coating and development system are achieved. Furthermore, in the coating and developing method, high printing performance can be obtained even when processing is performed with a small amount of a developing solution, so that the amount of waste liquid can be reduced.

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Claims (1)

(57) [Claims] 1. An undercoat layer and a silver halide emulsion on a support
Lithographic printing plate provided with a layer and a physical development nucleus layer in this order.
In the method of treatment using the salt diffusion transfer process, law
Acid, silicic acid, ascorbic acid, iminodiacetic acid, citric
It contains at least one kind of weak acid ion selected from acid, propionic acid and salts thereof (provided that 1
At least 0.1 mole of ascorbic acid per bottle
Except when it is contained as the main developer) , and the pH is 12
A method for processing a lithographic printing plate, characterized by using the above developer.